This invention relates to novel froth flotation frothers which demonstrate enhanced recovery of coarse particles in froth flotation.
Froth flotation is a commonly employed process for concentrating minerals from ores. In a flotation process, the ore is crushed and wet ground to obtain a pulp. A frothing agent, usually employed with a collecting agent, is added to the ore to assist in separating valuable minerals from the undesired or gangue portions of the ore in subsequent flotation steps. The pulp is then aerated to produce a froth at the surface thereof and the collector assists the frothing agent in separating the mineral values from the ore by causing the mineral values to adhere to the bubbles formed during this aeration step. The adherence of the mineral values is selectively accomplished so that the portion of the ore not containing mineral values does not adhere to the bubbles. The mineral-bearing froth is collected and further processed to obtain the desired minerals. That portion of the ore which is not carried over with the froth, usually identified as "flotation tailings", is usually not further processed for extraction of mineral values therefrom. The froth flotation process is applicable to ores containing metallic and nonmetallic mineral values.
In flotation processes, it is desirable to recover as much mineral values as possible from the ore while effecting the recovery in a selective manner, that is, without carrying over undesirable portions of the ore in the froth.
While a large number of compounds have foam or froth producing properties, the frothers most widely used in commercial froth flotation operations are monohydroxylated compounds such as C.sub.5-8 alcohols, pine oils, cresols and C.sub.1-4 alkyl ethers of polypropylene glycols as well as dihydroxylates such as polypropylene glycols. The frothers most widely used in froth flotation operations are compounds containing a nonpolar, water-repellant group and a single, polar, water-avid group such as hydroxyl (OH). Typical of this class of frothers are mixed amyl alcohols, methylisobutyl carbinol, hexyl and heptyl alcohols, cresols, terpineol, etc. Other effective frothers used commercially are the C.sub.1-4 alkyl ethers of polypropylene glycol, especially the methyl ether and the polypropylene glycols of 140-2100 molecular weight and particularly those in the 200-500 range. In addition, certain alkoxyalkanes, e.g., triethoxybutane, are used as frothers in the flotation of certain ores.
Although mineral recovery improvements from a preferred frother in the treatment of an ore can be as low as only about 1 percent over other frothers, this small improvement is of great importance economically since commercial operations often handle as much as 50,000 tons of ore daily. With the high throughput rates normally encountered in commercial flotation processes, relatively small improvements in the rate of mineral recovery result in the recovery of additional tons of minerals daily. Obviously then, any frother which promotes improved mineral recovery, even though small, is very desirable and can be advantageous in commercial flotation operations.
One well recognized problem in froth flotation is the inability of many commercial froth flotation processes to recover large particles of valuable minerals. Many of the frothers described hereinbefore demonstrate an inability to recover efficiently the coarse particles in a froth flotation process. What are needed are mining chemicals, for instance, frothers, which enhance the recovery of coarse particles while maintaining an efficient recovery for medium sized and fine particles.